Farming for the Hellfire Ring in Diablo RoS

Keys and Infernal Machines:
Note that you have to be at Torment I or better if you intend to farm these. You need one of each of the four keys to make the new Infernal Machines – at a cost of 100,000 gold – but you do at least get to choose which of the four portals. (This assumes you have RoS, but is similar in any case if you don’t have the expansion). To open the portals start the act 1 campaign quest ‘Return to New Tristram’ (or simply go to Tristram in adventure mode) and bash open the door behind Brother Malachi and use the appropriate device(s).

The recipe to craft the infernal machines can drop from any of the key wardens :

Odeg in the fields of Misery, Act I, drops the Key of Bones

Sokahr in the Dahlgur Oasis, Act II, drops the Key of Gluttony

Xag’rith in Stonefort, Act III, drops the Key of War

Nekarat in level 1 of the Silver Spire, Act IV, drops the Key of Evil

You may be happy to note that keywardens all have a small chance to drop a second key, though from another keywarden.

General tactics:
I assume you’ve faced all the ‘Ubers’ before and have an idea of each bosses attacks, but it’s always good to recap as I’ve helped in groups that have been hammered and eventually given up because they found the fights too hard. Simply kill the right bosses – and adds – in the right order and, if you have them, wear the right amulets for the corresponding fight and you’ll be fine. If you are still wiping, learn to dodge better and/or lower the level if you can. (Possible in private groups, not so in public parties).

The following neck pieces will be a great help:
Countess Julia’s Cameo give immunity to and healing from arcane attacks, countering most of Maghda’s attacks.

Mara’s Kaleidoscope has the same immunity bonus to poison and will help a limit with Ghom, though even at T6 I found his gasses bearable.
(Note that this ease is not the case in Rifts, especially at Torment 6 as his poison clouds takes no notice of your elemental resistance. Even after you’ve killed him, until his gas clears it can still very quickly kill you. With this amulet however he is largely powerless against you.)

The Star of Azkaranth does the same with fire and will help with Diablo and with Kulle who often joins the last fight.

Though not really needed here, the other immunity items include the Talisman of Aranoch (Cold), the Xephirian Amulet (Lightning) and the incredibly rare Ice Climber boots, which give immunity to freeze attacks.

Infernal Machine of Bones opens up the Realm of Discord where you face Leoric and Maghda who drop Leoric’s Regret organ.

Tactics:
Concentrate first of Leoric, who is the weakest of all the ‘Ubers’, keeping on top of his summon minions. Then go after Maghda. Again, as her health falls she’ll shield herself and summon minions with freeze attacks. Clear these, then go back to her.

Infernal Machine of Gluttony opens the Realm of Chaos, battling Rakanoth and Ghom in return for a Vial of Putridness organ.

Infernal Machine of War opens up the Realm of Turmoil. Here Siegebreaker and Zoltan Kulle drop the Idol of Terror organ.

Tactics:
To be honest I can never remember the best way for this fight, but generally melee go after the Siege breaker and casters and hunters go after Kulle. If you have all caster classes, or all melee get rid of the Siegebreaker first as he’s the weaker of the two.

Infernal Machine of Evil opens up a portal to the Realm of Fright and the hardest fight, this one against Diablo and random Ubers. Drops Heart of Evil organ.

Tactics:
Apparently most people give up because of this fight. It’s not actually hard (at the right level) but it does require thought, concentration and co-ordination. Even in a clan run I found this frustrating, despite repeatedly explaining the fight before, during and after each battle. If you follow these instructions carefully, you’ll be fine!
First rule:
From 100 to 75% he is weak, even at the highest level. You don’t need to blow all your cooldowns. Also, as you get him to 75% you want to be moving aways, relaying on ranged attacks as much as possible.
At 75% he stuns everyone and summons another ‘Uber’ so you now have two of them – plus any minions – after you. The previous tactics from earlier fights apply, only moreso. And this is why most pugs and disorganised runs fails. People don’t think, they don’t act as a team.
Second rule:
Ignore Diablo completely until the area is otherwise clear. Yes, dodge and heal from his attacks but under no circumstances attack him. Deal with whoever he’s summoned – and any and all adds they summon – and make sure everyone is alive and healed. Then, and only then attacks Diablo again.
At 50% he’ll summon someone else to help him. Same deals
At 25% To be honest I’m not sure if this is buggy or how it’s meant to be but you end up with 3 Dialbo attacking you. Perhaps it depends on the number in the party. Regardingless by now he should be easy to kill. This is easiest with ranged AoE attacks with pets and turrets. Hit, run, heal, hit again. Kiting. Preferring casters anyway and lacking the fire amulet I’ve not tried going mano-a-mano but that would probably work too for self-healing melee builds.

Note in there the reason pugs fail: You always get one muppet that knows better and just stays on Diablo, all the time. You get someone in the group like that, leave them dead, them kick them… Otherwise you can end up with a nightmare like Kulle bouncing round throwing tornadoes, fireballs and slowness domes, Maghda dropping arcane turrets all over the place, throwing insect spawns and summoning ever more minions who are dropping freezes plus three Diablo raking the entire area in fire.

Once you have all four parts (and the recipe from Squirt in act II) you can finally make a level 70 Hellfire Ring which adds 45% increase to your experience bonus and, like it’s predecessor, is usable by level one characters. Rinse and repeat for other character classes and/or better rolls. The whole process does rather highlight the repetitive nature of the game.

Cautionary note : As you can see, unlike the ‘legacy’ Hellfire ring you cannot choose the primary stats, so you might want to craft it on the character or general class it’s intended for.

I’d test it thoroughly myself except, really, it’s just not worth the effort unless you have a lot of characters to level up. Repeatedly kill a keywarden over and over again to get a key or two then repeat for the other three keys. Then face the bosses that may or may not drop the parts you need – and repeat this for each of the four organs you need. After all this you get a random ring that might have awful enchants – especially given the outrageous cost to re-roll on rings and amulets.

If you are determined on this course, it’s best to do it in clan runs with associates and friends you can trust. If you all farm 4 of each key (16 in all) – enough for four Infernal Machines each – that gives you 16 portals in all which, at T3 should guarantee you all get at least one ring. When my clan did it (some at t6, some at t4) most people got one ring each, one lucky person got enough for three rings. That’s RNG for you.

As I said, it does reply on trust, but here’s how I organised it for the clan I’m in:

First run, each of the four portals.
Second run mostly the Discord realm (Infernal Machines of Bones) as everyone needed Leoric’s Regret.
Each run after that concentrated on who needed what for the first ring and, after that, which Uber boss most people needed for the second ring, carrying on until all 16 machines had been used.

The ‘old’ Hellfire ring is still available if you don’t have the expansion – or if you join groups still doing those portals. The only difference is the random nature of the portals, the fights are a lot easier and there’s only 3 keys and portals to sort not 4. The other difference is Nekarat in level 1 of the Silver Spire, Act IV. At level 60 he can drop the recipe and a random key. Once you have the recipe you can ignore him – or farm him for keys if you like that level.